Document Detail


Peripheral vascular adaptation and orthostatic tolerance in Fontan physiology.
MedLine Citation:
PMID:  19841302     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: The Fontan circulation is critically dependent on elevated venous pressures to sustain effective venous return. We hypothesized that chronically increased systemic venous pressures lead to adaptive changes in regional and peripheral vessels to maintain cardiac output, especially when patients are upright.
METHODS AND RESULTS: Nine post-Fontan procedure patients (aged 13 to 24 years) and 6 age- and sex-matched controls were compared with techniques to measure circulatory responses (peripheral and compartmental blood flow, venous capacity, and microvascular filtration). Parameters studied included strain-gauge plethysmography measures of peripheral circulatory function, regional blood volume distribution by impedance plethysmography, and head-up tilt testing. Important differences between Fontan patients and controls were seen in several vascular compartments: (1) Calf capacitance was lower (median, 3.5 versus 5.5 mL/100 mL tissue; P=0.005), and resting venous pressure was higher (13.0 versus 10.5 mm Hg; P=0.004); (2) higher leg arterial resistance was observed (32.1 versus 22.2; P=0.03); (3) microvascular filtration pressures and threshold for edema were elevated; and (4) with head-up tilt testing, splanchnic flow was not reduced in Fontan patients versus controls (fractional change, +4% versus -32%; P=0.004), and splanchnic arterial resistance did not increase as expected (fractional change, +8% versus +79%; P=0.003).
CONCLUSIONS: Reduced venous compliance and increased filtration thresholds may act as adaptive mechanisms in maintaining venous return in Fontan circulation. Well-compensated Fontan subjects demonstrate superior orthostatic tolerance resulting from decreased compartmental fluid shifts in response to head-up tilt and higher vascular resistance. This results from increased venous stiffness and decreased splanchnic capacitance and may also be an adaptive mechanism to maintain venous return in these patients while standing.
Authors:
Usha S Krishnan; Indu Taneja; Michael Gewitz; Richard Young; Julian Stewart
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-10-19
Journal Detail:
Title:  Circulation     Volume:  120     ISSN:  1524-4539     ISO Abbreviation:  Circulation     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-03     Completed Date:  2009-12-30     Revised Date:  2013-05-31    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1775-83     Citation Subset:  AIM; IM    
Affiliation:
Department of Pediatric Cardiology, New York Medical College, Valhalla, NY 10595, USA. usha_krishnan@nymc.edu
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological*
Adolescent
Blood Circulation
Blood Vessels / physiology*
Case-Control Studies
Dizziness
Fontan Procedure*
Hemodynamics
Humans
Orthostatic Intolerance*
Plethysmography
Posture
Regional Blood Flow
Young Adult
Grant Support
ID/Acronym/Agency:
R01 HL074873-05/HL/NHLBI NIH HHS; R01 HL087803-01A1/HL/NHLBI NIH HHS; R01HL074873/HL/NHLBI NIH HHS; R01HL087803/HL/NHLBI NIH HHS; R21 HL091948-01/HL/NHLBI NIH HHS; R21HL091948/HL/NHLBI NIH HHS
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